media: i2c: adv748x: afe: fix sparse warning

This fixes the following sparse warning:

drivers/media/i2c/adv748x/adv748x-afe.c:294:34:    expected unsigned int [usertype] *signal
drivers/media/i2c/adv748x/adv748x-afe.c:294:34:    got int *<noident>
drivers/media/i2c/adv748x/adv748x-afe.c:294:34: warning: incorrect type in argument 2 (different signedness)
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/i2c/adv748x/adv748x-afe.c

@@ -275,7 +275,8 @@ static int adv748x_afe_s_stream(struct v4l2_subdev *sd, int enable)
 {
 	struct adv748x_afe *afe = adv748x_sd_to_afe(sd);
 	struct adv748x_state *state = adv748x_afe_to_state(afe);
-	int ret, signal = V4L2_IN_ST_NO_SIGNAL;
+	u32 signal = V4L2_IN_ST_NO_SIGNAL;
+	int ret;
 
 	mutex_lock(&state->mutex);